Some of the drugs that have been seized as part of Operation Challenger. Credit: Greater Manchester Police

As part of the operation, there has been more than 300 arrests, £2m worth of property seized, more than £300,000 worth of drugs recovered and £650,000 worth of restraint orders since October 2012.

Chief Constable Sir Peter Fahy said: "The investigation into the murders of Fiona, Nicola and the Short family revealed a far-reaching web of organised criminality and extreme violence which had to be tackled.

"The historic rivalry between criminal factions fighting over reputation and territory and creating alternative systems of justice was the spark that led to the tragic events we saw last year.

"Over the past few years, we have made huge strides towards tackling organised crime. Millions of pounds worth of drugs have been seized and more than 1,500 years of jail time handed out to offenders.

"However, we know there are still criminalnetworks causing misery to certain communities so Operation Challenger seeks tobuild on our successes and permanently tackle these organised crimegroups."

Dale Cregan was subjected to twice-daily checks behind his false eye as part of the intensive security operation surrounding his trial.

Nothing was left to chance for the ring of steel thrown around Preston Crown Court which cost more than £5 million.

Dale Cregan has been jailed for a whole life term. Credit: Police Handout.

All Category A inmates transported to court need to undergo a strip search and in Cregan's case that included his left eye socket - a time-consuming extra check which is said to have annoyed the killer.

A source at HMP Manchester, better known as Strangeways, said: "Every time he comes in and every time he goes out of the building he must be searched and checked - including behind his eye.

"Because he is a category A prisoner, each time he leaves these walls he is strip searched and he must take his eye out so we can look behind it for drugs or some sort of weapon or anything he shouldn't have.

"And every time he comes back from court he gets strip searched again and he has to take his eye out again."

Cregan is thought to have lost his eye in a fight with police in Thailand which involved a knuckle-duster.